Several types of stretchable cargo straps are known and have been widely used in both light- and heavy-duty applications. For example, light-duty cargo straps have been employed to hold miscellaneous small articles in place on the luggage carriers of bicycles. Somewhat heavier duty cargo straps have been employed to secure a wide variety of articles, such as skis, surfboards, sailboards, other small craft, ladders, pipes, lumber and various other materials to car top carriers and to the overhead racks of pickups and other vehicles. Even heavier straps, referred to as "bungee cords" have been employed to secure aircraft to the decks of aircraft carriers.
These stretchable, flexible cargo straps generally comprise an elongated, stretchable first member, such as a band of rubbery elastomer material having a rectangular, circular or other cross-section and composed of one or more strands of the elastomeric material. Typically an attachment means such as a hook is provided as each end of the band, by means of which the strap may be hooked to the cargo object, to another object or to itself. For example, in employing such a strap it is a common practice to pass the center portion of the strap over a cargo object while passing the ends of the strap around a fixed support and then hooking on to the center portion of the strap with the hook. In some embodiments, the band of elastomeric material is provided with a close fitting outer layer woven of threads or filaments to protect the band against abrasion.
Such cargo straps have been subject to important limitations or difficulties which have been recognized for many years. For example, these cargo straps are subject to breakage with resultant damage to or loss of the cargo object as a result of over-stressing or aging of the elastomeric material. Where the cargo object is one of substantial value, such as for example a surfboard or sailing board which is attached to a car top carrier on a fast moving vehicle, the resulting damage can be catastrophic if the breakage of the strap results in the watercraft separating from the vehicle. Such occurrences also result in significant hazards, with attendant property damage and the potential for serious injury to the occupants of following vehicles.
Another difficulty exists in relation to the practice of passing the hook on such a cargo strap around a support and then hooking the hook to the central portion of the cargo strap. Because the hook has the ability to slide along the central portion of the cargo strap to which it is hooked, it is difficult to maintain the desired amount of restoring force in the cargo strap if the strap happens to be somewhat longer than the minimum length required to pass over or around the cargo object.
Still another difficulty lies in the fact that typically, cargo straps do not provide any significant degree of security against theft of the cargo object. This is a particularly serious shortcoming where it is desired to use such a strap to bind valuable property to an exterior carrier, such as a car or truck top carrier.
The longstanding nature of these problems and the minimal changes that have occurred in cargo straps over a period of many years stand as mute testimony to the fact that practical and economic solutions to these problems have not been obvious. The present invention is aimed at providing solutions to any or all of the foregoing problems, and also provides additional solutions and advantages discussed below.